Heterolytic H₂ Activation by Nonmetals

Abstract

Nice cleavage: Two new strategies for the transition‐metal‐free activation of σ bonds are presented, namely, Bertrand's activation of dihydrogen by carbenes (see picture, left) and Stephan's “frustrated” Lewis acid/base pairs (right; R=Me3C6H2).

Hydrogen and Amine Activation by a Frustrated Lewis Pair of a Bulky N‐Heterocyclic Carbene and B(C6F5)3

“…The generated C 6 F 5 H and unreacted ItBu were observed by 19 F and 1 H NMR spectra. The observation of a broad signal centered around 33 ppm in the 11 B NMR spectra for 6-8 suggest three-coordinate monomeric aminoboranes. In addition, restricted rotation about the newly formed covalent B À N bond is evident in the 19 F NMR spectra.…”

A Stable but Highly Reactive Phosphine‐Coordinated Borenium: Metal‐free Dihydrogen Activation and Alkyne 1,2‐Carboboration

“…Indeed, besides FLP, a few main group compounds have been shown to split H 2 at a unique reactive site. [16] Bertrand et al pioneered the field with ambiphilic acyclic and cyclic amino carbenes, [17] Aldridge and co-workers generalized the approach to aminoboryl and aminosilyl silylenes, [18] and Piers et al extended the field to highly electron-deficient antiaromatic boroles [2a] (see Refs. [19,20] for additional examples).…”

Dihydrogen Activation by Antiaromatic Pentaarylboroles

“…1 Recently, interest in more environmentally benign, transition metal-free systems for activation of dihydrogen [2][3][4] has spiked, 5 primarily spurred by the development of the "Frustrated Lewis Pairs" (FLPs) concept. [6][7][8] In FLPs, Lewis acid/base combinations sterically prevented from forming strong classical adducts are capable of heterolytically activating H2.…”